Text 1991, 305 rader
Skriven 2005-08-16 08:00:18 av WAYNE CHIRNSIDE (1:123/140)
     Kommentar till en text av MARK LEWIS
Ärende: NASA, shuttle, anyone?
==============================
-> -> not according to what i've seen... it was the backup sensor 
-> -> to the backup sensor that failed in the testing done during 
-> -> the launch countdown... they were unable to reproduce the 
-> -> failure during later testing after going into the system to 
-> -> try to track down the failure...     

->  WC> Every sensor is the backup for the other three and that's a fact. 

-> oh? so which one is the primary? and where is this fact stated?

All four are the primary and three  are the backups to the one
that may give an anomalous reading.

-> [trim]

-> ->  WC> Had the sensors failed again as they had before as nothing 
-> ->  WC> had been done to fix them it's possible the sensors would 
-> ->  WC> have indicated fuel it was running out.

-> ->  WC> This would lead to the flame from the engine nozzels being 
-> ->  WC> sucked back into the combution chambers, BOOM.

-> -> wrong... the indication of lack of fuel would shut down the 
-> -> engines and they would not have made it to orbit... 
->     
->  WC> I expressed myself poorly.

-> not a problem... been done many time before by all of us O:)

->  WC> Had the sensors indicated fuel when there was none the shutdown
->  WC> signal would not be sent and the situation I described could have
->  WC> occured. It's why those sensors exist in the first place, or so
->  WC> said a NASA engineer.

-> right... however, the problem was that the sensor(s) were indicating no fuel
-> when there was a full tank... so different problem, actually...

Well as thye never determined _what_ caused the sensor problem 
there's no way to predict any way a future failure might have manifested
itself.


-> -> the failure was a "no fuel" indication when
-> -> the tanks had fuel... not an indication of fuel when there was none...

->  WC> Any intermittent failure is unpredictable and with a half million 
->  WC> gallons of liquid hydrogen and oxygen there's little room for
->  WC> error. 

-> with a _known_ full tank and one sensor telling them it is empty, that
sounds
-> pretty predictable to me...

That a critcal compnent had failed yes.
Sometimes the sensor indicated fuel, other times not.

->  WC> The chief Morton Thiokol engineer had authority to stop the
->  WC> shuttle Challenger from flying due to his expressed concerns about
->  WC> the cold's effects onthe o ring seals in the SRB's.

->  WC> He was overruled and the shuttle Challenger blew up.
->  WC> Being an embarrassment for telling the truth he was fired shortly
->  WC> thereafter.

->  WC> Engineers, quite a few of them, expressed deep concern about the
->  WC> deris that hit the Columbia's wing after liftoff. The lower rank 
->  WC> engineers had no avenue to express their concerns to flight 
->  WC> managers. Later their e-mails all came out revealing their 
->  WC> concerns very early on after the liftoff. Another shuttle lost by 
->  WC> ignoring evidence at hand :-(

-> yes, i've extremely aware of all this (other than the engineer being
fired)...
-> i have archived recordings and texts of much of it, if not all of it... i'm
-> very into this stuff and have a couple of satelite dishes set up where i can
-> specifically acquire the NASA TVRO signals... the 10 foot mesh has two sets
of
-> recievers connected so that i can watch/record two channels off one bird...
the
-> other dish is a direct tv dish that i get the same as one of the channels
off
-> the 10 foot mesh... i won't even mention the "tracking" dish i have
connected
-> to a soundcard and tracking software for grabbing images and other data
-> transmitted O:)                                      

Sure seems you're into it!
I've followed the space program since Atlas and Redstones
and the first Mercury capsules.

I've also looked into the Bell X-craft program that was before my time
by researching the internet.

-> ->  WC> This is generally considered a bad thing.

-> ->  WC> Also a repair to a dent in the shuttle's tank was repaired after
-> ->  WC> the foam was removed. Foam was replaced but it was deemed 
-> ->  WC> unnecessary to inspect the affected area.

-> ->  WC> As it happens foam from this area detached during launch to orbit. 

-> -> i have the video and pictures... the problem i have with what you
-> -> are saying is that the same thing happened on the other side of the 
-> -> tank where the other SRB was mounted... so that's two foam 
-> -> detachments... not just one... methinks that some are confusing some 
-> -> things...                       

->  WC> There were FIVE foam detachments, one was just over a pound
->  WC> and had it struck the orbiter earlier in denser air it could have
->  WC> disabled it for a sucessful landing.

-> that is a possibility, yes... i agree... however, we're talking about the
large
-> (two of them) detachments that came off back around the bottom SRB mounts...
-> those had little chance to harm the shuttle...

-> -> ->  WC> Shuttle not rolled back but delayed.

-> -> -> so... don't have to rollback to fix a problem...               

-> ->  WC> Don't worry they didn't. 

-> -> i'm not worried... i was saying that there does not have to be a
-> -> rollback to fix a problem... i left off the word "you" in front of 
-> -> "don't"...

->  WC> You do if you want to go inside the tank where the fuel sensors are
->  WC> and actually diagnose what's wrong with them, or so said NASA. They
->  WC> flew on a wing and a prayer instead.

-> obviously you don't because they didn't... they pulled the sensor(s) and
-> connected them to testing hardware and had at them for days... 
   
Nope, they wrang out the wires, swapped pairs and ran diagnostics.
To actually examine the fuel sensors one has to empty the tank, clear it
and enter the tank and that would have to have taken place in the
vehical assembly building.

-> when they
-> discovered nothing, they put them back in place and tested again for more
-> days... still nothing showed up...  

They never moved them out of place, they're _inside_ the tank.
They swapped wire pairs, ran diagnostics and speculated on
what _might_ have been wrong with the bad sensor.

-> oh, and who said they had to roll back to get inside the tank(s)?? i'm sure
-> there are accessible man hatches somewhere on the vehicle... at least if the
-> sensors are inside the tank(s)...             

Source: NASA as reported by local NBC affiliate.
I'm in Florida so get pretty good shuttle coverage.
I've been to the Cape twice taking the tour.

-> ->  WC> They flew the shuttle without a clue as to what had caused the
-> ->  WC> problem. 

-> -> ->  WC> Intermittent problem with the faulty fuel sensor never pinned 
-> -> ->  WC> down it happened to be working when they launched after 
-> -> ->  WC> deciding to override their own safety rules.

-> -> -> when did they decide to override their rules? i don't recall that 
-> -> -> and i watched and recorded most all of the NASA TV broadcasts...     

-> ->  WC> It was repeatedly announced after the initial delay and after they
-> ->  WC> failed to pin down the intermittent fuel sensor problem,

-> -> it was announced that they were overridding their safety rules?? i
-> -> definitely do not remember that specific wording...


->  WC> They said they would fly with three operating sensors in direct
->  WC> violation of safety regulations requiring all four be working. 

-> interesting... i dunno if i'll go digging about for that, though... it is
not
-> that important, really... the mission flew and was highly successful... i
have
-> absolutely no problem with that at all...

The backup orbiter's fuel tank sensors had shown the same erratic
behavior previously.

-> ->  WC> It just happpened the sensor didn't fail during the runup to
-> ->  WC> launch, very fortuitous.

-> -> are you positive that it was a sensor failure? they aren't...
                                                                  
No way to be *positive* as the sensors were never examined.
I'd _guess_ a grounding problem but that's all it'd be is a guess.
If I had the go - no go responsibility I wouldn't launch on a guess.

In all likelyhood one more catastrophic failure kills the program.
There are 19 more needed launches to finish the international space
station and one Hubble service call and that's cuting it close.

It also puts the odds based on past performance of another catastrophic
failure at near .60 certainty.
They could all go off flawlessly or we could have another shuttle
break up.

->  WC> they were getting a false reading intermittently and they checked
->  WC> the wiring and swapped the wires from differing sensors never
->  WC> finding the source of the failure.

-> that still doesn't point to the sensor being the problem... were they able
to
-> get the error any more after they first got into the wiring?? i don't
believe
-> so... however, there's a lot that they haven't told everyone in their
-> conferences and press meetings...

Intermittents can go away for random intervals of time only to crop up
when least expected.
I've got a monitor like that in the other room.
I know what it is and need to ficx it but haven't gotten around to it.
It's one of those odd rare intermittents that clearly points to where it
resides.

-> [trim]

->  WC> I finally found the ground fault, it was in the high - low beam
->  WC> selector button on the floor and a new one cured the problem.

-> glad you found that or we'd not be having this _friendly_ discussion today
;)

-> -> ->  WC> Now the tank's burned up returning to Earth we'll never know why
-> -> ->  WC> the sensor malfunctioned.

-> -> -> one suggestion was a ground problem because the problem never
-> -> -> happened after the initial discovery... could also have been a 
-> -> -> loose connection... either way, they apparently fixed it while 
-> -> -> getting to it and studying it...              

Or not, we'll never know.

->  WC> Could have been this, could have been that, could have been
->  WC> anything. Know what blew up Apollo 13's service module that nearly
->  WC> killed the crew and aborted their moon landing?

-> yup, sure do...

->  WC> There was a heater in one of the oxygen tanks to vaporize the
->  WC> liquid O2 to fuel the fuel cells in the cold of space.
->  WC> That heater was specified to be 24 volts, it wasn't.
->  WC> It was spec'd 12 volts. An astronaut following standard procedure  
->  WC> turned on the heater and a moment later the stirrer,
->  WC> Seconds later the oxygen tank expoded taking much of the
->  WC> desperately needed service module with it.
->  WC> Astronauts lived in the LEM lander sick and cold in that craft not
->  WC> designed for the job to save what little was left of the capsule
->  WC> for the last monments of re-entry.

-> yes, i've read the reports and seen the movie many times <shrug> ;)

I followed it on T.V. as well.
                                           
-> ->  WC> Ground problems are FAR from trivial as an electrical _circuit_
-> ->  WC> requires a return to function. In my personal experience ground 
-> ->  WC> problems are actually the worst sort of problem.

-> -> yes, they can be... i've done my fair share of them over the years ;)

->  WC> They can kill you rather quickly even here on Earth.

-> yup... i've been a ground more than i care to think about... i really hate
-> being the ground path when discharging picture tubes... that's one bite that
-> hurts like hell... not only is high voltage a problem, but so is high
-> amperage... i can cause some real pain with 9 volts and a high amount of
-> ampreage O:)
                              
Make up a discharge wand using high tension high voltage wire
like the anode wire, put a high value resister in line, have an
insulated handle and flat conducting surface to slide under the 
anode cup to discharge prior to pulling the anode lead.

Being a tad paranoid about such things I used a series high value
resistor in series with a lower value one with a neon bulb 
across the smaller resistor as a visual indication of discharge.

Of course before I rigged up the device I got hit hard, dislocated my
shoulder, put my elbow through the hollow closet door behind me
and briefly passed out.
Motivation.
That was up north, here in Saint Pete Florida with the humidity less of
a problem.

-> ->  WC> I spent months tracking down an intermittent ground problem in  a
-> ->  WC> stereo amplifier once.

-> -> -> what else was sloppy??

-> ->  WC> See above.

-> -> besides that...

->  WC> They launched in spite of the known problems.

-> and that was sloppy? sounds almost corporate or government to me ;)

Well the Defense Department became involved in NASA during the shuttle
program, that could explain a lot.
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